CARBIDE INJECTION FOR THE EAF
Utilizing chemical energy for heating is not news to the steel industry. Injecting calcium carbide into electric furnaces or the BOF was proposed back in the 1960's, and first major trials occurred in the 1980's.
As of this writing, Carbide Industries has been involved with six carbide injection trials, all of which proved successful. One company developed a full SOP for their EAF and utilized carbide injection on hundreds of heats, averaging 5,000 lbs per day of carbide injection. A well-executed quantitative trial at another EAF shop showed a 5% reduction in kWh/heat, 8% reduction in oxygen usage, 5% reduction in power-on time, 7% shorter tap-to-tap time, 11% higher slag basicity, and 1.3% higher billet yield.
These impressive numbers are great news for companies that have high local electrical power cost, or are in need of producing more steel per shop-hour - even those that are already using injected fuels.
Electric power is stolen from the EAF whenever carbon and lime are injected to produce a foamy slag. Carbide, unlike carbon, does not require energy to produce CO. And as opposed to injecting lime at room temperature, carbide's exothermic reaction produces lime already at steelmaking temperature. In fact, the theoretical scrap melting ability of carbide exceeds 6 pounds of iron produced per pound of carbide injected.
At the end of the heat, carbide injection can also be used to recover iron, manganese, and other alloys from the slag prior to tapping. In the stainless steel EAF the metallic recovery savings are even more impressive. Carbide is much more cost effective than ferrosilicon, silicon carbide, or aluminum at reducing chromium from the slag, while drastically lowering lime consumption, and providing a more stable and longer lasting foamy slag.
In addition to the savings from electricity, lime, carbon, oxygen, and reduced tap-tap time, carbide injection also showed in the trials to reduce gunning, increase refractory life, increase tap hole life, and reduce the amount of ladle deoxidizers.
CI welcomes the opportunity to discuss with you the reasons why these shops saw savings and productivity increases and to provide an initial estimate of your cost savings. Please contact:
- Greg Brasel, Technical Manager (502) 775 - 4133
- Dr. Stewart Robinson, Product Development Manager (502) 775 - 4202
- George Jansen, Sales Manager (502) 775 - 4205
- Rich Dippolito, Sales Manager (502) 775 - 4210
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